一、parent、self、$this、__CLASS__
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class A {}
class B extends A{
parent::(public|protected)(静态方法|静态变量) ===> parent永远是A
self::(public|protected)(静态方法|静态变量) ===> self永远是B
$this->(public|protected)(非静态方法|非静态变量) ===> $this永远是B的是实例化对象
__CLASS__ ===> 永远是B
} class C extends B{
parent::(public|protected)(静态方法|静态变量) ===> parent永远是B
self::(public|protected)(静态方法|静态变量) ===> self永远是C
$this->(public|protected)(非静态方法|非静态变量) ===> $this永远是C的是实例化对象
__CLASS__ ===> 永远是C
} |
二、static::
static关键字可以实现以下功能：
1 调用类的静态方法 有后期静态绑定效果；大理石构件维修厂家
2 调用类的静态属性 有后期静态绑定效果；
3 调用类的非静态方法 没有后期静态绑定效果；
4 注意：不可以调用非静态属性；
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class A {
private static function foo() {
echo "A success!\n";
}
public function test() {
$this->foo();
}
} class B extends A {
} class C extends A {
private static function foo() {
echo "C success!\n";
}
} $b = new B();
$b->test();//A success!
$c = new C();
$c->test();//A success!
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class A {
private static function foo() {
echo "A success!\n";
}
public function test() {
static::foo();
}
} class B extends A {
} class C extends A {
private static function foo() {
echo "C success!\n";
}
} $b = new B();
$b->test();//A success!
$c = new C();
$c->test();//A无法调用C里的私有foo方法
//将C的foo改成非private(public|protected)就可以解决class A {
private static function foo() {
echo "A success!\n";
}
public function test() {
static::foo();
}
} class B extends A {
} class C extends A {
public static function foo() {
echo "C success!\n";
}
} $b = new B();
$b->test();//A success!
$c = new C();
$c->test();//C success!
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class A {
public static function foo() {
static::who();
}
public static function who() {
echo __CLASS__."\n";
}
} class B extends A {
public static function test() {
A::foo();
parent::foo();
self::foo();
}
public static function who() {
echo __CLASS__."\n";
}
}class C extends B {
public static function who() {
echo __CLASS__."\n";
}
} C::test(); A =>A::foo()的结果C =>parent::foo()能走到A的foo,里面static::who找C::who
C =>self::foo()能走到B的foo,B继承A,走到A的foo,里面static::who找C::who
class A {
protected static function foo() {
static::who();
}
protected static function who() {
echo __CLASS__."\n";
}
} class B extends A {
public static function test() {
A::foo();
parent::foo();
self::foo();
}
protected static function who() {
echo __CLASS__."\n";
}
}class C extends B {
protected static function who() {
echo __CLASS__."\n";
}
} C::test(); //A C C,解释同上
class A {
public static function foo() {
static::who();
}
private static function who() {
echo __CLASS__."\n";
}
} class B extends A {
public static function test() {
A::foo();
parent::foo();
// self::foo();
}
private static function who() {
echo __CLASS__."\n";
}
}class C extends B {
private static function who() {
echo __CLASS__."\n";
}
} C::test();//A =>A::foo()的结果 //报错 A不可C的私有方法who => parent::foo()能走到A的foo,里面static::who找C::who,C的who只能在C里调用，不能在A里调用//报错 A不可C的私有方法who => self::foo()能走到B的foo,B继承A,走到A的foo,里面static::who找C::who,C的who只能在C里调用，不能在A里调用 |
三、new static()
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//new self()与new static()的区别，官网例子如下： class A {
public static function get_self() {
return new self();
}
public static function get_static() {
return new static();
}
} class B extends A {}
echo get_class(B::get_self()); // A
echo get_class(B::get_static()); // B
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